Plastic molding involves filling a mold cavity with a plastic material that is fluidized by heat and pressure and allowed to solidify, thus producing an object or plastic part. One of the common molding methods utilizes a molding press having two halves of a mold attached to two platens of the press, one of which is moved relative to the other by a hydraulic ram. The platens are heated such as by steam or electricity to supply heat to the mold. The cavities are filled with a predetermined amount of plastic material either in pellet form or preforms such as rolled SMC material and pressure is applied to bring the platens and mold halves together. The heat and pressure fluidize the plastic material as the mold is slowly closed. In many cases the molding press is horizontal which means that the two platens carrying the mold halves are movable horizontally relative to each other to open and closed positions. There are generally two types of plastic materials, thermosets and thermoplasts. In the case of thermosets the material "sets up" or cures with the application of heat, while in the case of thermoplasts they require cooling for complete solidification. In plastic molding processes utilizing a horizontal press it is desirable to have the preform plastic material inserted into the mold cavity and have the finished molded product removed from the mold at the same time while the platens carrying the mold halves are in the open position. With this kind of an arrangement the cycle time for successive molding operations is shortened, thus allowing increased capacity for the molding press.
Molding operations have used gantry supported robots to remove molded objects or parts from the mold when the platens of the press are open but heretofore the gantry support has been mounted on the floor which obstructs equipment access to the press and there has been no provision for loading the mold at the same time as the objects or parts that have been molded are being removed from the mold.
It is desirable that the floor area around horizontal molding presses be clear of fixed structures such as gantry supports so that press service equipment may be moved around and in close proximity to the molding press to remove the molds and replace them or for any other type of press maintenance that may be necessary. Wheeled equipment such as fork lifts are often required to maneuver in and around the press in order to periodically maintain and modify the press and the molds contained therein.
By this invention the above desirable characteristics of a horizontal plastic molding press operation including simultaneous loading and unloading the mold and maintaining an unobstructed floor area around the press are accomplished and in doing so, several other advantages attributed to this invention are also accomplished.